Currently, in the thin film transistor (TFT) LCD device, the LCD device is driven by reversing the polarity to prolong the life span of the liquid crystal. In the driving circuit of the LCD panel using the method to reverse the polarity, the control chip needs to control the voltage to the source of each data line to switch frequently between the positive voltage and negative voltage. Thus, the charging difference of the voltage is caused to be larger and is unfavorable to lower the power consumption of the LCD panel.
With reference to FIG. 1, to solve the aforementioned problem, in the conventional LCD device, it is usually to control the gating signals SELR, SELG, SELB as high voltage level when the charging timing starts. Thus, the TFTs corresponding to the electrodes of all of the R, G, B sub-pixels in each row are switched on simultaneously when progressive scanning and the electrodes of each sub-pixel are charged to GND voltage, i.e. 0V. Then the electrical potentials of the electrodes of all of the R, G, B sub-pixels in this row simultaneously become GND voltage. Then the gating signals SELR, SELR, SELB are controlled as high voltage level in sequence to switch on the corresponding TFTs of the R, G, B sub-pixels in sequence so that the electrodes of the sub-pixels are charged the pixel voltages with corresponding polarity one by one.
Therefore, in the driving circuit of the LCD panel using the method to reverse the polarity, the negative pixel voltages are charged to 0V simultaneously, and then are charged one by one to positive pixel voltages so that the charging difference of the voltages is not so large to lower the power consumption of the LCD panel.
However, generally the GND is not the median when switching the positive and negative pixel voltages. For example, assuming the public voltage is 1.2V, and then the positive and negative pixel voltages corresponding to the source voltage with grayscale brightness 128 are respectively 6V and −3.6V. If using the method that first charging the electrodes of each pixel to the GND voltage, the charging difference of the voltages reaches to 6V when charging from the GND voltage to the positive pixel voltage. Then the charging difference of the voltages is still large to cause the charging time to be longer and the power consumption to be larger.